Drug maker AstraZeneca has filed a suit in the United States that seeks to extend its exclusive rights on some forms of its antidepressant drug Seroquel until December.
The Anglo-Swedish company said Tuesday that it had filed its suit in the U.S. District Court in Washington, D.C.
The suit seeks to overturn a ruling last week by the U.S. Food and Drug Administration that generic copies of the drug would not have to carry the same warnings about possible side effects _ including suicidal thoughts and elevated blood sugar _ that were required of AstraZeneca.
The patent on the active ingredient in Seroquel and Seroquel XR expired in September.
Seroquel was AstraZeneca's second best-selling product, and the fifth biggest seller in the United States.